[Diy_efi] Info about GM Ecotec engine

[clair.davis at charter.net]

Ben,
You may also want to look at how the engine management systems for
flexible-fuel vehicles handle this problem.  I'm hardly an expert on
flexible fuels, but I think the primary alternative fuel I've seen has been
methanol (or propane for some fleet vehicles).  At least the fuel rails,
pressure regulator, and injectors from a FFV Dodge Spirit I found in the
salvage yard claimed to be methanol-compatible.  Methanol is pretty harsh,
and attacks seals, diaphragms, hoses, etc. if they're not formulated to
handle the fuel.
Then, on a FFV, there must be some way for the computer to determine which
fuel is being used.  How this is done, I have no idea, but there are a
number of ways of doing it.  Once it knows, the calibration is changed to
account for the fuel being burned.
Finally, since you're shooting for stoich, and you know how much fuel/oxygen
is consumed at stoich, you should be able to do some relatively
straight-forward math to determine what the increase in fuel demand will be.
Pulse width can get you there, but that removes much of the potential for
power enhancements in the future for a given injector size.  Bumping up the
injector size is another way, but very large injectors become hard to
control for short pulse widths (at idle, for example).  If you vary fuel
pressure AND pulse width, you give yourself some additional range of use.

If you haven't already, you may want to surf around on the EPA web site to
see if they've got something there for info on converting to alternative
fuels.  Sounds like an interesting project.  I wish we could have done
something that cool when I was in HS.

Clair
69 Valiant/7730
FTWTX

----- Original Message ----- 
From: <lmarcus2 at juno.com>
To: <diy_efi at diy-efi.org>
Sent: Tuesday, November 30, 2004 9:58 PM
Subject: [Diy_efi] Info about GM Ecotec engine


>
> Hello,
>
> I'm a 10th grader doing a project for an engineering competition, and I
need some advice on how to modify the GM Ecotec engine's fuel system to
acomodate ethanol fuel. I am have been told that increasing the pulse-width
on the injectors will result in the increased flow that is necessary for an
stoichiometric ethanol combustion. Are there others ways of acomplishing
increased fuel flow? And what are some software programs that would allow
modifications to be made to the fuel system. Any advice or suggestions in
this area would be extremely helpful because I am new to all of this. Thank
you,
>
> Ben Marcus
>
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